The path contained in the scene directs the OS to look up the exact location of the file in the File Allocation Table (FAT: Win9x, WinME, sometimes WinXP), the master file table (NTFS: Win2000/XP/Vista) or whatever the system is called in OSX. Then the OS will retrieve the file on behalf of the application.
This is how ALL file retrieval works, in EVERY app (unless the app overrides this behavior, as is the case with low level utilities such as disk defragmenters, virus scanners, disk imaging software and the like).
So Poser doesn't have to be slower than any other app when it comes to file retrieval. Unless it does some very inefficient processing before actually retrieving the file.

The pen is mightier than the sword. But if you literally want to have some impact, use a typewriter

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